Abstract BACKGROUND Tea gray blight caused by Pestalotiopsis and allied genera is a destructive disease worldwide, including in India. Although management with synthetic fungicides is a rapid approach, emerging fungicide resistance has become a serious problem for the tea industry. Hence, the present study investigated the efficacy of ethyl acetate (EA) extract and the formulation of Trichoderma reesei to control tea gray blight in India. In addition, the chemical profile of T. reesei and its influence on chitinase and β‐1,3‐glucanase genes were studied. RESULTS Trichoderma reesei EA extracts were highly effective (>70.1% growth inhibition) against Pseudopestalotiopsis theae at 100 and 200 μg mL −1 concentrations, suggesting production of potent antifungal volatiles. Gas chromatographic–mass spectrometric analysis of T. reesei EA extract identified 28 metabolites, with four major compounds accounting for >60% of total composition. Scanning electron microscopic analysis demonstrated the mycoparasitic nature of T. reesei to P. theae under laboratory conditions. Reverse transcription quantitative polymerase chain reaction analysis revealed that co‐inoculated plants with both T. reesei and P. theae expressed respective 2.7‐ and 2.6‐fold increases in chitinase and β‐1 , 3‐glucanase expressions relative to controls. A 2‐year field trial (2022 and 2023) of the T. reesei ‐based formulation (20% suspension concentrate) showed over 60.0% disease reduction at 1% and 2% concentrations compared to the control without phytotoxic effect. The formulation was viable for up to seven months with 5.3 × 10 6 CFU mL −1 population density. A higher disease reduction (>66.0%) was achieved with synthetic fungicides than with T. reesei‐ based formulation across locations and years, but no significant yield difference occurred between the two treatments. CONCLUSION The present results conclude that a T. reesei ‐based formulation could be a potential biocontrol candidate and a promising alternative to gray blight for sustainable tea production. © 2026 Society of Chemical Industry.
Pandey et al. (Sun,) studied this question.